Valve structure



May 10, 194.9 J. w. MARSH 2,470,041

VALVE STRUCTURE Filed Aug. 8, 1945 2 sheets-sheet 1 J. W. MARSHk VALVE STRUCTURE May l0, 1949.

Fild Aug. s, 1945 2 Sheets-Sheet 2 Fle Patented May 10, 1949 vUN 11T ED STATES PATENT UFF ICE STRUCTURE Johln Marsh, Alexandria, Va.

Application August 8, 1945, Serial No. 609,547

(Cl.r 30-353) 14 Claims. i.

This invention. relates to valve structures, andi relates more particularly to ya novel valve hav-ing a number oi uses including use asan independentl bra-ke valfve for automatic and manual. control: of locomotive brakes.. without the use @supplementary valves such as distributing, feed; reducingvk and 'safety valves.

It is among the olijectsv of .this invention .to provide a valve ot the 'type described which will automatically apply and. release locomotive brakes when a reduction or increase of train-line 'pres'- sure is` elected, and to permitl the application, release .andvariation of pressure on locomotive brakes independently of automatic action. A further object of this invention is to providev a valve which in 'a simple and direct manner com'- lainesthe functions ot the independent and distributing. Valvev with their auxiliary rappurte-f nancesf, normally used for the automatic and independent control of locomotive brakes. Another' object ofl the invention is the provision of' a valve ot the type 'described of the selflappingy type which willi automatically maintain any desired locomotive bra'ke-cylinder pressure, and which is simple to construct, understand, operate` andI maintain. A valve embodying the present inventionmay be used Wherever it is desired to maintain: a predetermined ihn-dv pressure on' any means proportionate to they liuid pressure applied? to a secondmeans, and to further control' the proportion of ii-'uid pressure applied tothe first meansa The apparatus presently used for automatic and independent control of locomotive brakes comprisesv a distributing valve' communicating witlr an automatici brake valve and an independent brake Valve, a reducing valve, a safety Vai-ve and a double-'heading cock,y the. construction; operation and arrangement of which are wellY knownv to those' versedf4 in the art.

In' the drawings.-

Fig. l is a central, vertical sedtion taken, through. a self-lapping, independent airebrake Valve embodying the presentv invention.

Figi. 2. is a section takenI on line 2'-21 of Fig. 1.

Fig. 3v is a broken section taken on line 3'-3 of Fig. 2'.

Fig. 4 is a horizontale section taken on line Il l of Fig. l.

Fig.A 5` is a. diagrammatic view of an air brake system'. having they valve yof the present invention included therein forv controlling. a locomotive brake.

The Seli-lapping, independent air'-brake Valve c'on-Ibining; theiunctons of. the.E conventional inde.v-

pendent'. brake valve, distributing valve and reservoir, is illustrated in: Figs. l to 41, inclusive. This valve combines 'the 'principles of the brake valve vand triple valve,l brak' f-lcylinder pressure being controlled by' train-.line pressure acting against .a spring, the'. spring load being. controlled by the operator.

The housing fior` this: val-ve is. yrcirmed in a plurality of sections. I Il, @112, `lf3 and H. Lower housing.A section'. 5M: is provided with. Aa control pressure port lII3 leading to tlfre train line. Housing section I 2f is provided with an inlet port I9 from the main reservoir tochamber 20, and also an outletiportzlZ I? Lconnecting the brake cylinder' with 22.. Valve y25, which is formed' with utcd slides; shown `at 2li inl Fig. #,ismounted for reciprocating movement in valve support 2l and is av double-'seated valve. itis provided; with al valve member 28 at' its lower end', which` is. seated vat 2.9', which constitutes a -'ied seat. At its' upper end it is `formed with a valve' member` 32; which: is seated at. 33, which constitutes 'a floating' seat.

A diaphragm. 36iszea1ried Aon the lower surface of a piston velement 3T which i's slidably mounted in pistonrcylinder '33 at the lower end of `housing section I4. The .marginal edges of diaphragm 36. are secured between housing sections I3 and AIft. Piston element 31 is formed on itsl lower sur- :tace with an extensionll having a central aperture 41,. constituting an 'exhaust conduit, valve seat 33 being formed 'at the lower endf of said exhaust conduit.. Another diaphragm 4'2 is mounted around; outer peripheral edges between; housing vse'rcti'ons IIZ and Ir3, and associated with the: upper surfaceoi this diaphragm isa piston element 44, 'and associated with the. lower surface-'of the diaphragm is a piston element'lS. The exhaust conduit 40 extends through the 'parts 36, 44,. 421 and' 45:

Piston elements 'M and yI5 are mounted on the exhaust conduit 40, and are secured thereon by means oi av nut 46: upper annular edge of upper piston element '44 secures the diaphragm 3u in sealed relation .relative toA piston' element 31. A spring 50 mounted within upper housing sectionl t4 engages'. at its. lower end a spring cap 5I having a central projection 52 on itsl lower surface which is received within a generally conical opening. in piston 31 communicating with conduit 50, 'such projection 52 aiding in centering the spring cap relativeto piston 31. The spring lcap is formed with: a vertical' aperture 53 which communicates with conduit 40?. Thus, when .valve member 32 unseate'd', press-ure' chamber 22 may be vented through apertures 41 and 53, and out through vent opening 48 to the external atmosphere. At its upper end, spring 58 engages a spring cap 55 having on its upper surface a ball portion `56 which is engaged by a sharp-pitched screw 51 mounted at the upper end of housing section I4. Relative downward and upward movement of screw 51 to load or unload spring 50 is eiected by a handle 58 keyed, as at 59, to such screw.

In the initial setting of the valve, the handle 58 is manipulated to put downward mechanical pressure on the spring and through the spring to the piston 31 until there is a balanced condition between the downward spring pressure and the i upward fluid pressure acting respectively on opposite sides of said piston.

Main reservoir pressure has access to chamber 20 through port 62, which chamber is normally closed to train-line control pressure port I8 by means of a check valve 63 which is seated at 64. Chamber 66 between diaphragms 36 and 42 is open to train-line pressure through port 61 (Fig. 3). From the foregoing, it will be seen that brake-cylinder pressure is controlled by trainline pressure acting against spring 58, such pressure acting against upper diaphragm 36. The spring load in spring 50 is controlled by the operator through the medium of handle 58. A plurality of aligned, vertical apertures are provided in the several housing sections which receive bolts (not shown) for assembling the housing structure.

When the valve is in running position, as when the locomotive is running, reduction in train-line pressure brought about in any usual or preferred manner, will close seat 33 and open seat 29 due to the reduction of pressure in chamber 66, such pressure acting on diaphragm 36. Thus, air from the main reservoir passes through port 62 and into chamber 20, past valve seat 29 into chamber 22, and thence to the brake cylinder. This lpassage of air continues until the pressures balance. The brake-'cylinder pressure, however, can be further governed by operating the valve handle to alter the spring pressure applied, thus decreasing or releasing such pressure, or to apply and release the locomotive brakes without reduction of train-line pressure. Check valve 63 is provided in order that the locomotive can be operated dead in a train, in which case the main reservoir acts as the auxiliary reservoir for the dead locomotive brakes, and the independent brake valve thus becomes the triple valve. locomotive brakes are applied from the main reservoir, check valve 63 being held seated.

With the valve handle in running position, as above stated, a predetermined downward pressure is exerted 4by spring 50 on piston 31 and associated elements, including diaphragm 33, piston elements 44, 45, diaphragm 42, and valve seat 33, thus closing seat 33 and opening seat 29. This permits fluid under pressure supplied from a suitable source, as a main reservoir, to flow from chamber past seat 29, through iiutes 26 in Valve to chamber 22, and to fluid-pressureutilizing means such as brake cylinders communicating with port 2|. The fluid pressure which thus accumulates in chamber 22 also acts upwardly against piston element and diaphragm 42, against the downward pressure of spring 50. Thus, when the fluid pressure in chamber 22 and communicating means acting on piston 45 and diaphragm 42, exerts sufcient upward pressure In the event of train line failure, the

to overcome the downward pressure of spring 58, piston 45 and associated elements will rise, permitting valve 28 to close seat 29 and prevent further flow of fluid from chamber 28.

Fluid. pressure from an associated source, such as the train line of an air-brake system, communicating through ports I8 and 61 with chamber 86, exerts a downward pressure on piston 44 and diaphragm 42, and exerts an upward pressure on diaphragm 36 and piston 31. The effective area of diaphragm 42 is` less than the effective area of diaphragm 36. Accordingly, the train-line pressure, acting conjointly with uid pressure in chamber 22, will oppose the downward pressure of spring 5U. When the train line is re-charged and such train-line pressure reaches a predetermined amount, piston 31 and seat 33 will be raised off valve 32, releasing uid pressure in chamber 22 and associated means, by the flow of fluid past seat 33 through ports 41, 53, 48 to exhaust. Thus, it will be apparent that any predetermined fluid pressure in chamber 22 and associated means is maintained by a controlled fluid pressure at port I8. It will also be clear that the unit fluid pressure in chamber 22, multiplied by the eiective area of diaphragm 42, will be equal to the downward pressure o spring 50, less the net upward pressure on piston 31 exerted by uid pressure in chamber 66, and less the net upward pressure exerted on valve 28 by uid pressures in chamber 28 and in chamber 22. Since the effective area of valve 28 is relatively small, the effect of the pressure on valve 28 is normally not appreciable.

For an understanding of the operation of the present invention, reference is made to Figure 5, wherein the valve of the present invention is indicated at 13 which is connected to a source of pressure 1I by a conduit 12 coupled to the valve 13 at the inlet port I9. A conduit 18 leads from the outlet port 2I of the valve to one end of the brake cylinder 11 of a locomotive brake. The control pressure port I8 of the valve is connected to a conduit 16 which leads to a train line conduit 15. The system also includes a valve 14 for use in controlling the train-line or brake line pressure, which valve may be of any well known or preferred type and may have the construction shown in my co-pending application Serial No. 596,657, now Patent No. 2,450,480, granted October 5, 1948. This Valve is connected by a conduit 16 with the train-line conduit 15 and preferably to the conduit 16 which is connected to the train line conduit 15. The valve 14 is also connected by the branch conduit 12 to the conduit 12 which is connected to the source of pressure 1I,

Referring to Figures 1 and 5, it will be explained that by manipulation of the handle of the valve 14, fluid pressure from the reservoir 1I may be conducted through the valve 14, the conduits 16' and 15 to the train-line conduit 15 for the purpose of charging the train-line to the desired pressure. While charging the train-line, the

v pressure from the tank 'I I, which is conducted pressure in said control pressure port, resiliently compressible means applied to said fluid-tight elements to oppose said uid pressure in said outlet port, means to operatively control the pressure exerted by said resiliently compressible means, an exhaust conduit extending through said huid-tight elements and leading from the brake chamber to the external atmosphere, a multiple valve element provided with a plurality of valve portions, a fixed seat for one of the valve portions normally closing the inlet ports to the brake chamber, and a valve seat provided on the inlet end of said exhaust conduit adapted to be closed by a second portion of the valve element, the xed seat of the valve element being opened by a reduction in control pressure acting between said diaphragms, thereby venting uid under pressure in the inlet port to aforesaid chamber and aforesaid outlet port.

2. A uid pressure control valve comprising a housing having a plurality of ports including an inlet port, an outlet port, and a control pressure port, a brake chamber communicating with said outlet port, a pair of fluid-tight elements of unequal area, said fluid-tight elements being interconnected for conjoint reciprocating movement, the exterior face of one of said fluid-tight elements being subject to uid pressure in said outlet pori'l and the interior faces of both of said elements being subject to fluid pressure in said control pressure port, resiliently compressible means applied to said fluid-tight elements to oppose said fluid pressure in said outlet port, means to operatively control the pressure exerted by said resiliently compressible means, an exhaust conduit carried by and extending through said huidtight elements a multiple valve element provided with a plurality of valve portions, a iixed seat for one of the valve portions normally closing the inlet port to the brake chamber, and a seat for the inlet end of the exhaust conduit adapted to be closed by a second portion of said valve element, the fixed seat of the Valve element being opened by reduction of fluid pressure in the control pressure port acting between said huid-tight elements, thereby venting fluid under pressure in said inlet port to said chamber and said outlet port.

3. A iluid pressure control valve comprising a housing having a plurality of ports including an inlet port, an outlet port, and a control pressure port, a brake chamber communicating with said outlet port, a pair of Huid-tight elements of unequal area, said uid-tight elements being interconnected for conjoint reciprocating movement, the exterior face of one of said fluid-tight elements being subject to fluid pressure in said outlet port and the interior faces of both of said elements being subject to fluid pressure in said control pressure port, resiliently compressible means applied to said huid-tight elements to oppose said iluid pressure in said outlet port, means to operatively control the pressure exerted by said resiliently compressible means, an exhaust conduit carried by and extending through said fluidtight elements, a multiple valve element provided with a plurality of valve portions, a fixed Seat for one of the valve portions normally closing the inlet port to the chamber, and a seat for the exhaust conduit adapted to be .closed by a second portion of said valve element, the xed seat of the valve element being opened by reduction of fluid pressure in the control pressure port acting between said fluid-tight elements, thereby venting fluid under pressure in said inlet port to said chamber and said outlet port, the effect of said fluid pressure reduction being subject to control by controllable variation of pressure on said resiliently compressible means.

4. A fluid pressure control Valve comprising a housing having a plurality of ports including an inlet port, a control pressure port and an outlet port, a chamber communicating with said outlet port, means within said -chamber to admit uid under pressure from said inlet port to said outlet port by and in proportion to reduction of fluid pressure in said pressure control port, and a check valve for said pressure control port and subject to pressure on opposite sides from said control and inlet ports respectively, said control pressure port whereby fluid under pressure may ow from said pressure control port to said inlet port when iiuid pressure in said pressure control port exoeeds uid pressure in said inlet port.

5. In a fluid pressure system having a source of fluid under pressure, a fluid pressure applying element, and means for controlling the flow of fluid under pressure from said source to said pressure applying element, the combination of a valve device for applying pressure in said pressure applying element comprising a housing having a pressure applying chamber connected with the means for applying uid pressure, said chamber being provided with a valve inlet port communicating with the source of uid pressure, and a pressure control inlet port communicating with said means for controlling the now of uid pressure, a pair of :duid-tight elements of unequal areas, said fluid-tight elements being interconnected for conjoint reciprocating movement, the

external face of one of said huid-tight elements being subject to fluid pressure within said chamber and the interior faces of both said elements being subjected to fluid pressure in said pressure control port, operatively controllable pressure means applied to said fluid-tight elements to oppose fluid pressure Within said chamber, and valving means within said chamber actuated by reduction of uid pressure betweeny applying element, the combination of a valve device for applying pressure in said pressure applying element through reduction in pressure from the source and comprising a housing having a pressure applying chamber and a plurality of ports including an inlet port communicating with the source of uid pressure, an outlet port communicating with the pressure applying element, and a fluid pressure control inlet port communicating with said means for controlling the ow of iluid pressure, a pair of spaced duid-tight elements of unequal areas and dening a closed compartment, said fluid-tight elements being interconnected for conjoint reciprocating movement, the external face of one of said fluid-tight elements being subject to uid pressure within said chamber and the interior faces of both said elements being subjected to fluid pressure in said pressure control port, an exhaust conduit carried by the iiuid-tight elements and leading from the chamber operatively controllable pressure meansy applied tol said huid-tight elements to oppose uid .pressure WithinV said chamber, a check valve positioned between said inletport and said pressure control port whereby -fluid lunder pressure flow from said pressure kcontrol port to said inlet. port When Huid pressure in said .pressure 'control .port exceeds fluid .pressure in said inlet port, and valving means Within said chamber operating under reduction of fluid pressure between said fluidetight elements to provide communication between said inlet port and. said out'- let port and operating under 'in-crease of iiuid .pressure between lsaid huid-tight elements to .provide communication from said chamber through said exhaust.

4l... In a fluid pressure system having a source of iiui'd under pressure, av pressure applying element, and means -for controlling the iiow of iuid under pressure from said source to said pressure applying element, the `'combination of a valve device for applying pressure in said pressure apply"- ing 'element and comprising a housing having a pressure applying lchamber and a plurality of ports. including an inlet .port rcommunicating with the source: of fluid pressure and an outlet port commuuicatingrfrom the chamber to the pressure appiying: element,.a .pair of iiuid-tight elements of unequal` areas,V the exterior face of one of said huid-tight elements; being subject to i'luid pressure in said rchamber andthe interior faces of said fluid-tight elements being subject to uid pressure from saidsource, operatively controllable pressure means; applied to said iluid-tight elementsy to oppose iluid.,pressure in said chamber,

and valving means 'Withinsaid-chamber for maintaining .pressure in said chamber by and in proportionate to reduction in iiuid pressureirom said source, vsaid .proportion being varied by aforesaid operatively controllable pressure means appi'ed to.` said duid-tight. elements.

8. In a fluid pressure system having a source of fluid under pressuraa fluid vpressure applying element, and means. for controlling the i'low of 'fluid under pressurefrom said; source to said pressure applying element, the 'combination of a valve device for applying pressure in said elementand comprising -a housing having a plurality oi ports including an inlet port communicating with said source.,A a control pressure port communicating with said pressure control means and an outlet port. communicating with said fluid pressure. applying element, a chamber communicating with said outlet port, a pair of fluid-tight elements of unequal area, said uid-tight elements being interconnected for conjoint reciprocating movement, the exterior face of one of said fluidetight elements being subject to ii-uid pressure iny said chamber and the interior faces of both of `said elements being subject toy fluid pressure in said control pressure port, resiliently compressible means applied to said fluid-tight elements to oppose fluid pressure in said chamber, means to operatively control the pressure exerted by said resiliently compressible means, an exhaust conduit carried by and extending through the fluid-tight elements and leading outwardly from the chamber, a multiple valve element provided with a plurality of valve portions, a iixed seat for one of the valve portions normally closing the inlet port to the chamber, and a seat for the exhaust conduit associated with the first fluidtght element adapted to be closed by a second portion of the valve element, the xed seat of the valve element being opened by reduction of uid pressure in the control pressure port, thereby ventingiiuid 'from the inlet port 'to the charia1i ber, the exhaust conduit seat bei-ng lopened by increase of fluid pressure in the 'control pressure port, thereby venting fluid yfrom the 'chamber to exhaust, the iiuid pressure in said 'chamber being maintained in proportion to reduction in pressure vfrom the source, said ,proportion being 'operatively controlled :by resiliently compfre'ssible means..

-a fluid pressure :system having a source of iiuidy under pressure, 'a pressure I*applying ele ment,V and means for' controlling the flow of uid under .pressure trom said source to said pressure applying; elementp the combination vof -a valve de vice for applying pressure in said/element and comprising a housing having -a plural-ity of ports including an inlet. port `corrmiunicati-ng with said source, a `con-trolpressure port Icommunicating with said pressure control. means and an outlet port 'communicating with said .pressure applying element, a chamber vcommunica'ting, with said outlet port, a pair oi fluid-'tight elements 'of Aecu'tal 'area said fluid-tight. Velements being interconnected for coni'omt. reciprocating movement, the exterior face of one of said fluid-tight elements being 'subject tofluid pressure in 4said Ichainber andthe interior faces of. bot-h of said 'elements being subecttoiuidpressurein said controly .pressure port, resiliently compressible means appliedto said uuid-tight elem-'ents to oppose -fluid' pressure in' said cir-lambert',y means tof operatively controlf the pressure exerted by said resiliently compressible means, the first fluid-tight element having an. exhaust port, a multiple valve element provided a plurality of Avalve portions, `a iixed Vseat for one of the valve portions `normal-ly closing the inletport. to the chambenand a seat for the exhaust port associated with the nrst fluid-tight element adapted to be closed by a second portion Aof the valve. element, thev .xed seat or the valve element being lcpr-ined by reduction of iiuifd pressure inthec'ontrol pressure port, thereby venting fluid from` theV inlet. port to the chamber, the.. exhaust. port seat being openedby increase 'of iiui'd., pressure inthe control pressure port, thereby venting. uuid from the chamber to exhaust,v the fluid .pressure in said chamber being maintained: in proportion 'to reduction in. fluid pressure from the source, said proportion being operatively controlled: by resiliently compressible meansfand #a -cheek 'valve .positioned between ysaid inlet. portand "saidf'controlf pressure port, whereby underpressure. may flow yfromV said pressure control port to said inlet port when iiuid 'pressure inrsai'd 4control pressure por-t exceeds uuid pressure inf'saidrinletport.

.10.. yA Valve.- for'control'l-ingv fluid pressure: in a pressure utilizing rrrearls,r said Valve comprising a' housing having; a plurality of ports. including an inlet por-t may be connected with :a sourcey ofL fluid under pressurey :acont-rol :pressure port which may be'conuected la meansfor controlling fluid pressure from a source, and an outlet port which may be connected with a pressure utilization means, a chamber communicating with said outlet. port, a rst fluid-tight diaphragm subject to iiuid pressure in said chamber, a second Huid-tight diaphragm of larger area than said first diaphragm, said diaphragms being spacedapart and interconnected for conjoint reciprocating movement within said housing, the space between said diaphragms being subject to the fluid pressure in said control pressure port, resiliently compressible means acting on said diaphragms to oppose fluid pressure in said chamber and means 't'ooperatively control pressure of said means,

the rst fluid-tight diaphragm having an exhaust port communicating with the external atmosphere, a multiple valve element provided with a plurality of valve portions and actuated by reciprocating movement of said diaphragms, a xed seat for one of the Valve portions normally closing the inlet port to the chamber, a seat for the exhaust port associated With the rst iluidtight diaphragm adapted to be closed by a second portion of the valve element, and a check valve positioned between said inlet port and said control pressure port to prevent flow of fluid under pressure from said inlet port to said control pressure port.

11. A uid pressure control valve for use in a luid pressure system having means for utilizing iiuid pressure, a source of uid pressure, a conduit providing communication between said source and said valve, and means for controlling fluid pressure in said conduit, said valve comprising a housing having a chamber communicating with said conduit and with said utilizing means, a plurality of uid-tight elements and capable of conjoint movement, one of said fluidtight elements being subject to conduit pressure and another of said fluid-tight elements being subject to pressure applied to the utilizing means,

'the effective areas of said fluid-tight elements being such that the sum of the total pressure eiected by a predetermined fluid pressure on said uid-tight element subject to conduit pressure, plus the total pressure eiected by a predetermined fluid pressure on said fluid-tight element subject to utilizing means pressure, is equal to a predetermined total pressure, means for applying elastic pressure on said fluid-tight elements substantially equal to aforesaid total pressure and means to operatively control said elastic pressure,

an exhaust port providing communication bel tween said chamber and the external atmosphere, an inlet port providing communication between said chamber and said conduit, and a multiple valve element actuated by said iluid-tight elements, adapted to close said exhaust port and open said inlet port consecutively when the combined fluid pressures on said fluid-tight elements are less than the operatively controlled elastic pressure opposing said uid pressures, to close said inlet port when said combined fluid pressures l' equal said operatively controlled elastic pressure, and to open said exhaust port when said combined fluid pressures exceed said operatively controlled elastic pressure.

12. In a fluid pressure system having a source of uid under'pressure, a pressure applying element, and means for controlling the flow of fluid under pressure from said source to said pressure applyingelement, the combination of a valve device for applying pressure in said element through reduction in controlled pressure and comprising 'a housing having a plurality of ports including an inlet port connected with the lsounce of lfluid pressure, a control port connected with said control means, an outlet port connected with said pressure applying element, and an exhaust port, a pair of fluid-tight elements positioned within said housing and having a space therebetween, said fluid-tight elements being interconnected for conjoint reciprocating movement therein, the space between said diaphragms being subject to fluid pressure in said control port, one of said fluid-tight elements being subject to fluid pressure in said outlet port, controllable means for applying resilient pressure on said uuid-tight elements to oppose said outlet port fluid pressure, and a valve actuated by said fluid-tight means whereby communication is eiected between said inlet port and said outlet port by downward movement of said valve elements, and whereby communication is effected between said outlet port and said exhaust port by upward movement of said huid-tight elements.

13. A fluid pressure control valve comprising a housing having a plurality of ports, a pair of spaced interconnected uid-tight elements of unequal areas positioned Within said housing and capable of conjoint reciprocating movement therein, means for applying elastic pressure on said fluid-tight elements, an inlet control port communicating with the space between said fluidtight elements, an outlet port communicating with one of said fluid-tight elements whereby fluid pressure in said outlet port opposes aforesaid elastic pressure, an inlet port and an exhaust port, and a valve element positioned betweent said inlet port and said outlet port, said valve element having a rst seat electing communication between said inlet port and said outlet port, and a second seat effecting communication between said outlet port and said exhaust port, said valve element being actuated by movement of said fluid-tight elements.

14. The valve recited in claim 13 and provided with a check valve for the control port and subject to iluid pressure on opposite sides from said control and inlet ports respectively, said check valve closing said control port when fluid pressure in said inlet port exceeds iluid pressure in said control port.

JOI-IN W. MARSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 971,207 Michel Sept. 27, 1910 1,932,079 Livingston Oct. 24, 1933 2,015,181 Hildebrand et al. Sept. 24, 1935 2,135,007 Kamcharovic Nov. 7, 1938 2,289,559 Turek July 14, 1942 

